They say the shooting happened at the Delaware Valley Charter High School in north Philadelphia on Friday afternoon.
Police Commissioner Charles Ramsey says the shooter was captured near his home but the gun hasn't been recovered. He says surveillance video shows a group of students hanging around when the shooting happened.
He says it's unclear if the shooting was accidental or intentional but it "doesn't look like an active shooter type of situation."
Authorities say a male student and a female student were shot. Each student was shot in an arm.
The students have been taken to a hospital near the school. Police say they're in stable condition.
A spokesman for the school district hasn't responded to a call seeking comment.
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